Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * lib/dma-noop.c
3 *
4 * Simple DMA noop-ops that map 1:1 with memory
5 */
6#include <linux/export.h>
7#include <linux/mm.h>
8#include <linux/dma-mapping.h>
9#include <linux/scatterlist.h>
10
11static void *dma_noop_alloc(struct device *dev, size_t size,
12 dma_addr_t *dma_handle, gfp_t gfp,
13 struct dma_attrs *attrs)
14{
15 void *ret;
16
17 ret = (void *)__get_free_pages(gfp, get_order(size));
18 if (ret)
19 *dma_handle = virt_to_phys(ret);
20 return ret;
21}
22
23static void dma_noop_free(struct device *dev, size_t size,
24 void *cpu_addr, dma_addr_t dma_addr,
25 struct dma_attrs *attrs)
26{
27 free_pages((unsigned long)cpu_addr, get_order(size));
28}
29
30static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
31 unsigned long offset, size_t size,
32 enum dma_data_direction dir,
33 struct dma_attrs *attrs)
34{
35 return page_to_phys(page) + offset;
36}
37
38static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
39 enum dma_data_direction dir, struct dma_attrs *attrs)
40{
41 int i;
42 struct scatterlist *sg;
43
44 for_each_sg(sgl, sg, nents, i) {
45 void *va;
46
47 BUG_ON(!sg_page(sg));
48 va = sg_virt(sg);
49 sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
50 sg_dma_len(sg) = sg->length;
51 }
52
53 return nents;
54}
55
56static int dma_noop_mapping_error(struct device *dev, dma_addr_t dma_addr)
57{
58 return 0;
59}
60
61static int dma_noop_supported(struct device *dev, u64 mask)
62{
63 return 1;
64}
65
66struct dma_map_ops dma_noop_ops = {
67 .alloc = dma_noop_alloc,
68 .free = dma_noop_free,
69 .map_page = dma_noop_map_page,
70 .map_sg = dma_noop_map_sg,
71 .mapping_error = dma_noop_mapping_error,
72 .dma_supported = dma_noop_supported,
73};
74
75EXPORT_SYMBOL(dma_noop_ops);